Which alignment angle is most likely to affect steering returnability?

Steering returnability primarily relates to the caster angle in a vehicle's front suspension system. Caster is the angle formed by the steering axis in relation to the vertical axis. When the caster angle is positive, it tends to enhance steering returnability, allowing the steering wheel to return to the center position after a turn. This is because a positive caster angle creates a self-centering effect, as the wheel's contact patch moves behind the center of the steering axis during a turn.

In contrast, other alignment angles like front toe and camber, while important for overall tire wear and vehicle stability, do not directly influence the steering wheel's ability to return to the center. Front toe adjustments affect vehicle tracking and tire wear, while camber influences how the tires make contact with the road during cornering, but neither provides the self-centering benefit that positive caster does. Rear toe, while also important for handling and stability, has even less direct influence on steering returnability than the front angles. Therefore, the caster angle is the most significant factor affecting how well the steering components return the steering wheel to a neutral position after turning.